selftests/bpf: run flow dissector tests in skb-less mode

Export last_dissection map from flow dissector and use a known place in
tun driver to trigger BPF flow dissection.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/tools/testing/selftests/bpf/flow_dissector_load.c b/tools/testing/selftests/bpf/flow_dissector_load.c
index 7136ab9..3fd83b9 100644 (file)
--- a/tools/testing/selftests/bpf/flow_dissector_load.c
+++ b/tools/testing/selftests/bpf/flow_dissector_load.c
@@ -26,7 +26,7 @@ static void load_and_attach_program(void)
        struct bpf_object *obj;
 
        ret = bpf_flow_load(&obj, cfg_path_name, cfg_section_name,
-                           cfg_map_name, &prog_fd);
+                           cfg_map_name, NULL, &prog_fd, NULL);
        if (ret)
                error(1, 0, "bpf_flow_load %s", cfg_path_name);
 

diff --git a/tools/testing/selftests/bpf/flow_dissector_load.h b/tools/testing/selftests/bpf/flow_dissector_load.h
index 41dd695..eeb48b6 100644 (file)
--- a/tools/testing/selftests/bpf/flow_dissector_load.h
+++ b/tools/testing/selftests/bpf/flow_dissector_load.h
@@ -9,10 +9,12 @@ static inline int bpf_flow_load(struct bpf_object **obj,
                                const char *path,
                                const char *section_name,
                                const char *map_name,
-                               int *prog_fd)
+                               const char *keys_map_name,
+                               int *prog_fd,
+                               int *keys_fd)
 {
        struct bpf_program *prog, *main_prog;
-       struct bpf_map *prog_array;
+       struct bpf_map *prog_array, *keys;
        int prog_array_fd;
        int ret, fd, i;
 
@@ -37,6 +39,16 @@ static inline int bpf_flow_load(struct bpf_object **obj,
        if (prog_array_fd < 0)
                return ret;
 
+       if (keys_map_name && keys_fd) {
+               keys = bpf_object__find_map_by_name(*obj, keys_map_name);
+               if (!keys)
+                       return -1;
+
+               *keys_fd = bpf_map__fd(keys);
+               if (*keys_fd < 0)
+                       return -1;
+       }
+
        i = 0;
        bpf_object__for_each_program(prog, *obj) {
                fd = bpf_program__fd(prog);

diff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
index 126319f..51758a0 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
+++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
@@ -1,5 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
+#include <error.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
 
 #define CHECK_FLOW_KEYS(desc, got, expected)                           \
        CHECK_ATTR(memcmp(&got, &expected, sizeof(got)) != 0,           \
@@ -140,13 +143,73 @@ struct test tests[] = {
        },
 };
 
+static int create_tap(const char *ifname)
+{
+       struct ifreq ifr = {
+               .ifr_flags = IFF_TAP | IFF_NO_PI | IFF_NAPI | IFF_NAPI_FRAGS,
+       };
+       int fd, ret;
+
+       strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+
+       fd = open("/dev/net/tun", O_RDWR);
+       if (fd < 0)
+               return -1;
+
+       ret = ioctl(fd, TUNSETIFF, &ifr);
+       if (ret)
+               return -1;
+
+       return fd;
+}
+
+static int tx_tap(int fd, void *pkt, size_t len)
+{
+       struct iovec iov[] = {
+               {
+                       .iov_len = len,
+                       .iov_base = pkt,
+               },
+       };
+       return writev(fd, iov, ARRAY_SIZE(iov));
+}
+
+static int ifup(const char *ifname)
+{
+       struct ifreq ifr = {};
+       int sk, ret;
+
+       strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+
+       sk = socket(PF_INET, SOCK_DGRAM, 0);
+       if (sk < 0)
+               return -1;
+
+       ret = ioctl(sk, SIOCGIFFLAGS, &ifr);
+       if (ret) {
+               close(sk);
+               return -1;
+       }
+
+       ifr.ifr_flags |= IFF_UP;
+       ret = ioctl(sk, SIOCSIFFLAGS, &ifr);
+       if (ret) {
+               close(sk);
+               return -1;
+       }
+
+       close(sk);
+       return 0;
+}
+
 void test_flow_dissector(void)
 {
+       int i, err, prog_fd, keys_fd = -1, tap_fd;
        struct bpf_object *obj;
-       int i, err, prog_fd;
+       __u32 duration = 0;
 
        err = bpf_flow_load(&obj, "./bpf_flow.o", "flow_dissector",
-                           "jmp_table", &prog_fd);
+                           "jmp_table", "last_dissection", &prog_fd, &keys_fd);
        if (err) {
                error_cnt++;
                return;
@@ -171,5 +234,40 @@ void test_flow_dissector(void)
                CHECK_FLOW_KEYS(tests[i].name, flow_keys, tests[i].keys);
        }
 
+       /* Do the same tests but for skb-less flow dissector.
+        * We use a known path in the net/tun driver that calls
+        * eth_get_headlen and we manually export bpf_flow_keys
+        * via BPF map in this case.
+        *
+        * Note, that since eth_get_headlen operates on a L2 level,
+        * we adjust exported nhoff/thoff by ETH_HLEN.
+        */
+
+       err = bpf_prog_attach(prog_fd, 0, BPF_FLOW_DISSECTOR, 0);
+       CHECK(err, "bpf_prog_attach", "err %d errno %d", err, errno);
+
+       tap_fd = create_tap("tap0");
+       CHECK(tap_fd < 0, "create_tap", "tap_fd %d errno %d", tap_fd, errno);
+       err = ifup("tap0");
+       CHECK(err, "ifup", "err %d errno %d", err, errno);
+
+       for (i = 0; i < ARRAY_SIZE(tests); i++) {
+               struct bpf_flow_keys flow_keys = {};
+               struct bpf_prog_test_run_attr tattr = {};
+               __u32 key = 0;
+
+               err = tx_tap(tap_fd, &tests[i].pkt, sizeof(tests[i].pkt));
+               CHECK(err < 0, "tx_tap", "err %d errno %d", err, errno);
+
+               err = bpf_map_lookup_elem(keys_fd, &key, &flow_keys);
+               CHECK_ATTR(err, tests[i].name, "bpf_map_lookup_elem %d\n", err);
+
+               flow_keys.nhoff -= ETH_HLEN;
+               flow_keys.thoff -= ETH_HLEN;
+
+               CHECK_ATTR(err, tests[i].name, "skb-less err %d\n", err);
+               CHECK_FLOW_KEYS(tests[i].name, flow_keys, tests[i].keys);
+       }
+
        bpf_object__close(obj);
 }

diff --git a/tools/testing/selftests/bpf/progs/bpf_flow.c b/tools/testing/selftests/bpf/progs/bpf_flow.c
index 75b17ca..81ad9a0 100644 (file)
--- a/tools/testing/selftests/bpf/progs/bpf_flow.c
+++ b/tools/testing/selftests/bpf/progs/bpf_flow.c
@@ -64,6 +64,25 @@ struct bpf_map_def SEC("maps") jmp_table = {
        .max_entries = 8
 };
 
+struct bpf_map_def SEC("maps") last_dissection = {
+       .type = BPF_MAP_TYPE_ARRAY,
+       .key_size = sizeof(__u32),
+       .value_size = sizeof(struct bpf_flow_keys),
+       .max_entries = 1,
+};
+
+static __always_inline int export_flow_keys(struct bpf_flow_keys *keys,
+                                           int ret)
+{
+       struct bpf_flow_keys *val;
+       __u32 key = 0;
+
+       val = bpf_map_lookup_elem(&last_dissection, &key);
+       if (val)
+               memcpy(val, keys, sizeof(*val));
+       return ret;
+}
+
 static __always_inline void *bpf_flow_dissect_get_header(struct __sk_buff *skb,
                                                         __u16 hdr_size,
                                                         void *buffer)
@@ -109,10 +128,10 @@ static __always_inline int parse_eth_proto(struct __sk_buff *skb, __be16 proto)
                break;
        default:
                /* Protocol not supported */
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
        }
 
-       return BPF_DROP;
+       return export_flow_keys(keys, BPF_DROP);
 }
 
 SEC("flow_dissector")
@@ -139,8 +158,8 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
        case IPPROTO_ICMP:
                icmp = bpf_flow_dissect_get_header(skb, sizeof(*icmp), &_icmp);
                if (!icmp)
-                       return BPF_DROP;
-               return BPF_OK;
+                       return export_flow_keys(keys, BPF_DROP);
+               return export_flow_keys(keys, BPF_OK);
        case IPPROTO_IPIP:
                keys->is_encap = true;
                return parse_eth_proto(skb, bpf_htons(ETH_P_IP));
@@ -150,11 +169,11 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
        case IPPROTO_GRE:
                gre = bpf_flow_dissect_get_header(skb, sizeof(*gre), &_gre);
                if (!gre)
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                if (bpf_htons(gre->flags & GRE_VERSION))
                        /* Only inspect standard GRE packets with version 0 */
-                       return BPF_OK;
+                       return export_flow_keys(keys, BPF_OK);
 
                keys->thoff += sizeof(*gre); /* Step over GRE Flags and Proto */
                if (GRE_IS_CSUM(gre->flags))
@@ -170,7 +189,7 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
                        eth = bpf_flow_dissect_get_header(skb, sizeof(*eth),
                                                          &_eth);
                        if (!eth)
-                               return BPF_DROP;
+                               return export_flow_keys(keys, BPF_DROP);
 
                        keys->thoff += sizeof(*eth);
 
@@ -181,31 +200,31 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
        case IPPROTO_TCP:
                tcp = bpf_flow_dissect_get_header(skb, sizeof(*tcp), &_tcp);
                if (!tcp)
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                if (tcp->doff < 5)
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                if ((__u8 *)tcp + (tcp->doff << 2) > data_end)
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                keys->sport = tcp->source;
                keys->dport = tcp->dest;
-               return BPF_OK;
+               return export_flow_keys(keys, BPF_OK);
        case IPPROTO_UDP:
        case IPPROTO_UDPLITE:
                udp = bpf_flow_dissect_get_header(skb, sizeof(*udp), &_udp);
                if (!udp)
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                keys->sport = udp->source;
                keys->dport = udp->dest;
-               return BPF_OK;
+               return export_flow_keys(keys, BPF_OK);
        default:
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
        }
 
-       return BPF_DROP;
+       return export_flow_keys(keys, BPF_DROP);
 }
 
 static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
@@ -225,7 +244,7 @@ static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
                return parse_ip_proto(skb, nexthdr);
        }
 
-       return BPF_DROP;
+       return export_flow_keys(keys, BPF_DROP);
 }
 
 PROG(IP)(struct __sk_buff *skb)
@@ -238,11 +257,11 @@ PROG(IP)(struct __sk_buff *skb)
 
        iph = bpf_flow_dissect_get_header(skb, sizeof(*iph), &_iph);
        if (!iph)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        /* IP header cannot be smaller than 20 bytes */
        if (iph->ihl < 5)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        keys->addr_proto = ETH_P_IP;
        keys->ipv4_src = iph->saddr;
@@ -250,7 +269,7 @@ PROG(IP)(struct __sk_buff *skb)
 
        keys->thoff += iph->ihl << 2;
        if (data + keys->thoff > data_end)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        if (iph->frag_off & bpf_htons(IP_MF | IP_OFFSET)) {
                keys->is_frag = true;
@@ -264,7 +283,7 @@ PROG(IP)(struct __sk_buff *skb)
        }
 
        if (done)
-               return BPF_OK;
+               return export_flow_keys(keys, BPF_OK);
 
        return parse_ip_proto(skb, iph->protocol);
 }
@@ -276,7 +295,7 @@ PROG(IPV6)(struct __sk_buff *skb)
 
        ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
        if (!ip6h)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        keys->addr_proto = ETH_P_IPV6;
        memcpy(&keys->ipv6_src, &ip6h->saddr, 2*sizeof(ip6h->saddr));
@@ -288,11 +307,12 @@ PROG(IPV6)(struct __sk_buff *skb)
 
 PROG(IPV6OP)(struct __sk_buff *skb)
 {
+       struct bpf_flow_keys *keys = skb->flow_keys;
        struct ipv6_opt_hdr *ip6h, _ip6h;
 
        ip6h = bpf_flow_dissect_get_header(skb, sizeof(*ip6h), &_ip6h);
        if (!ip6h)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        /* hlen is in 8-octets and does not include the first 8 bytes
         * of the header
@@ -309,7 +329,7 @@ PROG(IPV6FR)(struct __sk_buff *skb)
 
        fragh = bpf_flow_dissect_get_header(skb, sizeof(*fragh), &_fragh);
        if (!fragh)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        keys->thoff += sizeof(*fragh);
        keys->is_frag = true;
@@ -321,13 +341,14 @@ PROG(IPV6FR)(struct __sk_buff *skb)
 
 PROG(MPLS)(struct __sk_buff *skb)
 {
+       struct bpf_flow_keys *keys = skb->flow_keys;
        struct mpls_label *mpls, _mpls;
 
        mpls = bpf_flow_dissect_get_header(skb, sizeof(*mpls), &_mpls);
        if (!mpls)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
-       return BPF_OK;
+       return export_flow_keys(keys, BPF_OK);
 }
 
 PROG(VLAN)(struct __sk_buff *skb)
@@ -339,10 +360,10 @@ PROG(VLAN)(struct __sk_buff *skb)
        if (keys->n_proto == bpf_htons(ETH_P_8021AD)) {
                vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
                if (!vlan)
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                if (vlan->h_vlan_encapsulated_proto != bpf_htons(ETH_P_8021Q))
-                       return BPF_DROP;
+                       return export_flow_keys(keys, BPF_DROP);
 
                keys->nhoff += sizeof(*vlan);
                keys->thoff += sizeof(*vlan);
@@ -350,14 +371,14 @@ PROG(VLAN)(struct __sk_buff *skb)
 
        vlan = bpf_flow_dissect_get_header(skb, sizeof(*vlan), &_vlan);
        if (!vlan)
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        keys->nhoff += sizeof(*vlan);
        keys->thoff += sizeof(*vlan);
        /* Only allow 8021AD + 8021Q double tagging and no triple tagging.*/
        if (vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021AD) ||
            vlan->h_vlan_encapsulated_proto == bpf_htons(ETH_P_8021Q))
-               return BPF_DROP;
+               return export_flow_keys(keys, BPF_DROP);
 
        keys->n_proto = vlan->h_vlan_encapsulated_proto;
        return parse_eth_proto(skb, vlan->h_vlan_encapsulated_proto);